We hope you've gotten the message that a low-fat diet with limited quantities of fried foods is good for your health. However, the same doesn't necessarily hold true for your car.

Biodiesel is a type of fuel made from cooking oil and grease. Any car with a diesel engine can run on it -- but don't start wringing the napkins from your last McDonald's run into your fuel tank. In order to power the car, the oil and grease need to be converted into biodiesel through a chemical process.

The process itself can actually be done at home. In fact, a lot of biodiesel enthusiasts make their own fuel using cooking oil from local restaurants. However, there is a little risk involved with the process. If you get it wrong, you could do a lot of damage to your vehicle (not to mention your house and yourself). Before trying to make biodiesel on your own, it's a good idea to train for a while with someone who's successfully done it before.

Biodiesel enthusiasts swear by the stuff. Not only is it much cheaper and cleaner than fossil diesel, but it'll make your car smell like french fries, too. No kidding! Just make sure you and your car can handle it before you brew up a batch.